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ElseCaseInsteadOfExhaustiveWhenSpec.kt
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ElseCaseInsteadOfExhaustiveWhenSpec.kt
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package io.gitlab.arturbosch.detekt.rules.bugs
import io.gitlab.arturbosch.detekt.rules.KotlinCoreEnvironmentTest
import io.gitlab.arturbosch.detekt.test.compileAndLintWithContext
import io.gitlab.arturbosch.detekt.test.lintWithContext
import org.assertj.core.api.Assertions.assertThat
import org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment
import org.junit.jupiter.api.Nested
import org.junit.jupiter.api.Test
@KotlinCoreEnvironmentTest
class ElseCaseInsteadOfExhaustiveWhenSpec(private val env: KotlinCoreEnvironment) {
private val subject = ElseCaseInsteadOfExhaustiveWhen()
@Nested
inner class Enum {
@Test
fun `reports when enum _when_ expression used as statement contains _else_ case`() {
val code = """
enum class Color {
RED,
GREEN,
BLUE
}
fun whenOnEnumFail(c: Color) {
when (c) {
Color.BLUE -> {}
Color.GREEN -> {}
else -> {}
}
}
"""
val actual = subject.compileAndLintWithContext(env, code)
assertThat(actual).hasSize(1)
}
@Test
fun `reports when enum _when_ expression contains _else_ case`() {
val code = """
enum class Color {
RED,
GREEN,
BLUE
}
fun whenOnEnumFail(c: Color) {
val x = when (c) {
Color.BLUE -> 1
Color.GREEN -> 2
else -> 100
}
}
"""
val actual = subject.compileAndLintWithContext(env, code)
assertThat(actual).hasSize(1)
}
@Test
fun `does not report when enum _when_ expression does not contain _else_ case`() {
val code = """
enum class Color {
RED,
GREEN,
BLUE
}
fun whenOnEnumPassA(c: Color) {
when (c) {
Color.BLUE -> {}
Color.GREEN -> {}
Color.RED -> {}
}
val x = when (c) {
Color.BLUE -> 1
Color.GREEN -> 2
Color.RED -> 3
}
}
fun whenOnEnumPassB(c: Color) {
when (c) {
Color.BLUE -> {}
Color.GREEN -> {}
}
}
"""
assertThat(subject.lintWithContext(env, code)).isEmpty()
}
}
@Nested
inner class `Sealed class` {
@Test
fun `reports when sealed _when_ expression used as statement contains _else_ case`() {
val code = """
sealed class Variant {
object VariantA : Variant()
class VariantB : Variant()
object VariantC : Variant()
}
fun whenOnSealedFail(v: Variant) {
when (v) {
is Variant.VariantA -> {}
is Variant.VariantB -> {}
else -> {}
}
}
"""
assertThat(subject.compileAndLintWithContext(env, code)).hasSize(1)
}
@Test
fun `reports when sealed _when_ expression contains _else_ case`() {
val code = """
sealed class Variant {
object VariantA : Variant()
class VariantB : Variant()
object VariantC : Variant()
}
fun whenOnSealedFail(v: Variant) {
val x = when (v) {
is Variant.VariantA -> "a"
is Variant.VariantB -> "b"
else -> "other"
}
}
"""
assertThat(subject.compileAndLintWithContext(env, code)).hasSize(1)
}
@Test
fun `does not report when sealed _when_ expression does not contain _else_ case`() {
val code = """
sealed class Variant {
object VariantA : Variant()
class VariantB : Variant()
object VariantC : Variant()
}
fun whenOnSealedPass(v: Variant) {
when (v) {
is Variant.VariantA -> {}
is Variant.VariantB -> {}
}
}
"""
assertThat(subject.lintWithContext(env, code)).isEmpty()
}
}
@Nested
inner class `Expected sealed class` {
@Test
fun `does not report when _expect_ sealed _when_ expression used as statement contains _else_ case`() {
val code = """
expect sealed class Variant {
class VariantA : Variant
class VariantB : Variant
class VariantC : Variant
}
fun whenOnSealedFail(v: Variant) {
when (v) {
is Variant.VariantA -> {}
is Variant.VariantB -> {}
else -> {}
}
}
"""
assertThat(subject.lintWithContext(env, code)).isEmpty()
}
@Test
fun `does not report when _expect_ sealed _when_ expression contains _else_ case`() {
val code = """
expect sealed class Variant {
class VariantA : Variant
class VariantB : Variant
class VariantC : Variant
}
fun whenOnSealedFail(v: Variant) {
val x = when (v) {
is Variant.VariantA -> "a"
is Variant.VariantB -> "b"
else -> "other"
}
}
"""
assertThat(subject.lintWithContext(env, code)).isEmpty()
}
}
@Nested
inner class Boolean {
@Test
fun `reports when boolean _when_ expression used as statement contains _else_ case`() {
val code = """
fun whenOnBooleanFail(b: Boolean) {
when (b) {
true -> {}
else -> {}
}
}
"""
val actual = subject.compileAndLintWithContext(env, code)
assertThat(actual).hasSize(1)
}
@Test
fun `reports when nullable boolean _when_ expression contains _else_ case`() {
val code = """
fun whenOnNullableBooleanFail(b: Boolean?) {
val x = when (b) {
true -> 1
false -> 2
else -> 100
}
}
"""
val actual = subject.compileAndLintWithContext(env, code)
assertThat(actual).hasSize(1)
}
@Test
fun `does not report when boolean _when_ expression does not contain _else_ case`() {
val code = """
fun whenOnBooleanPassA(b: Boolean) {
when (b) {
true -> {}
false -> {}
}
val x = when (b) {
true -> 1
false -> 2
}
}
"""
assertThat(subject.compileAndLintWithContext(env, code)).isEmpty()
}
@Test
fun `does not report when nullable boolean _when_ expression does not contain _else_ case`() {
val code = """
fun whenOnNullableBooleanPassA(b: Boolean?) {
when (b) {
true -> {}
false -> {}
null -> {}
}
val x = when (b) {
true -> 1
false -> 2
null -> 100
}
}
"""
assertThat(subject.compileAndLintWithContext(env, code)).isEmpty()
}
}
@Nested
inner class `Standard when` {
@Test
fun `does not report when _else_ case is used for non enum or sealed _when_ expression`() {
val code = """
fun whenChecks() {
val x = 3
val s = "3"
when (x) {
0, 1 -> print("x == 0 or x == 1")
else -> print("otherwise")
}
when (x) {
Integer.parseInt(s) -> print("s encodes x")
else -> print("s does not encode x")
}
when (x) {
in 1..10 -> print("x is in the range")
!in 10..20 -> print("x is outside the range")
else -> print("none of the above")
}
val y = when(s) {
is String -> s.startsWith("prefix")
else -> false
}
when {
x.equals(s) -> print("x equals s")
x.plus(3) == 4 -> print("x is 1")
else -> print("x is funny")
}
}
"""
assertThat(subject.compileAndLintWithContext(env, code)).isEmpty()
}
}
}